<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        a:link{
            display: block;
            width: 93px;
            height: 29px;
            background-image: url("img/link.png");
        }
        a:hover{
            background-image: url("img/hover.png");
        }
        a:active{
            background-image: url("img/active.png");
        }
        /*
            图片属于网页中的外部资源,外部资源都需要浏览器单独发送请求加载
                浏览器加载外部资源时是按需加载的,用则加载，不用则不加载
         */
    </style>
</head>
<body>
<a href="javasript:;"></a>
</body>
</html>